One-fifth of seats on a broad swath of public-company boards are now held by women, a sign of change as US corporations face increased pressure to diversify. The share of female board members in the Russell 3000 index, which includes most public companies on major US stock exchanges, increased to 20% in the second quarter of this year from 19% the previous quarter, according to Equilar, a governance-data firm. When Equilar began tracking the measure in late 2016, 15% of board seats were filled by women...